7 research outputs found
Antitubercular Nanocarrier Combination Therapy: Formulation Strategies and <i>in Vitro</i> Efficacy for Rifampicin and SQ641
Tuberculosis (TB) remains a major
global health concern, and new
therapies are needed to overcome the problems associated with dosing
frequency, patient compliance, and drug resistance. To reduce side
effects associated with systemic drug distribution and improve drug
concentration at the target site, stable therapeutic nanocarriers
(NCs) were prepared and evaluated for efficacy <i>in vitro</i> in Mycobacterium tuberculosis-infected
macrophages. Rifampicin (RIF), a current, broad-spectrum antibiotic
used in TB therapy, was conjugated by degradable ester bonds to form
hydrophobic prodrugs. NCs encapsulating various ratios of nonconjugated
RIF and the prodrugs showed the potential ability to rapidly deliver
and knockdown intracellular M. tuberculosis by nonconjugated RIF and to obtain sustained release of RIF by hydrolysis
of the RIF prodrug. NCs of the novel antibiotic SQ641 and a combination
NC with cyclosporine A were formed by flash nanoprecipitation. Delivery
of SQ641 in NC form resulted in significantly improved activity compared
to that of the free drug against intracellular M. tuberculosis. A NC formulation with a three-compound combination of SQ641, cyclosporine
A, and vitamin E inhibited intracellular replication of M. tuberculosis significantly better than SQ641 alone
or isoniazid, a current first-line anti-TB drug
Probing Molecular Packing of Lipid Nanoparticles from <sup>31</sup>P Solution and Solid-State NMR
Lipid
nanoparticles (LNPs) are intricate multicomponent systems
widely recognized for their efficient delivery of oligonucleotide
cargo to host cells. Gaining insights into the molecular properties
of LNPs is crucial for their effective design and characterization.
However, analysis of their internal structure at the molecular level
presents a significant challenge. This study introduces 31P nuclear magnetic resonance (NMR) methods to acquire structural
and dynamic information about the phospholipid envelope of LNPs. Specifically,
we demonstrate that the 31P chemical shift anisotropy (CSA)
parameters serve as a sensitive indicator of the molecular assembly
of distearoylphosphatidylcholine (DSPC) lipids within the particles.
An analytical protocol for measuring 31P CSA is developed,
which can be implemented using either solution NMR or solid-state
NMR, offering wide accessibility and adaptability. The capability
of this method is demonstrated using both model DSPC liposomes and
real-world pharmaceutical LNP formulations. Furthermore, our method
can be employed to investigate the impact of formulation processes
and composition on the assembly of specifically LNP particles or,
more generally, phospholipid-based delivery systems. This makes it
an indispensable tool for evaluating critical pharmaceutical properties
such as structural homogeneity, batch-to-batch reproducibility, and
the stability of the particles
Antitubercular Nanocarrier Combination Therapy: Formulation Strategies and in Vitro
ABSTRACT: Tuberculosis (TB) remains a major global health concern, and new therapies are needed to overcome the problems associated with dosing frequency, patient compliance, and drug resistance. To reduce side effects associated with systemic drug distribution and improve drug concentration at the target site, stable therapeutic nanocarriers (NCs) were prepared and evaluated for efficacy in vitro in Mycobacterium tuberculosis-infected macrophages. Rifampicin (RIF), a current, broad-spectrum antibiotic used in TB therapy, was conjugated by degradable ester bonds to form hydrophobic prodrugs. NCs encapsulating various ratios of nonconjugated RIF and the prodrugs showed the potential ability to rapidly deliver and knockdown intracellular M. tuberculosis by nonconjugated RIF and to obtain sustained release of RIF by hydrolysis of the RIF prodrug. NCs of the novel antibiotic SQ641 and a combination NC with cyclosporine A were formed by flash nanoprecipitation. Delivery of SQ641 in NC form resulted in significantly improved activity compared to that of the free drug against intracellular M. tuberculosis. A NC formulation with a three-compound combination of SQ641, cyclosporine A, and vitamin E inhibited intracellular replication of M. tuberculosis significantly better than SQ641 alone or isoniazid, a current first-line anti-TB drug
In Situ Characterization of Pharmaceutical Formulations by Dynamic Nuclear Polarization Enhanced MAS NMR
A principal
advantage of magic angle spinning (MAS) NMR spectroscopy
lies in its ability to determine molecular structure in a noninvasive
and quantitative manner. Accordingly, MAS should be widely applicable
to studies of the structure of active pharmaceutical ingredients (API)
and formulations. However, the low sensitivity encountered in spectroscopy
of natural abundance APIs present at low concentration has limited
the success of MAS experiments. Dynamic nuclear polarization (DNP)
enhances NMR sensitivity and can be used to circumvent this problem
provided that suitable paramagnetic polarizing agent can be incorporated
into the system without altering the integrity of solid dosages. Here,
we demonstrate that DNP polarizing agents can be added in situ during
the preparation of amorphous solid dispersions (ASDs) via spray drying
and hot-melt extrusion so that ASDs can be examined during drug development.
Specifically, the dependence of DNP enhancement on sample composition,
radical concentration, relaxation properties of the API and excipients,
types of polarizing agents and proton density, has been thoroughly
investigated. Optimal enhancement values are obtained from ASDs containing
1% w/w radical concentration. Both polarizing agents TOTAPOL and AMUPol
provided reasonable enhancements. Partial deuteration of the excipient
produced 3Ă higher enhancement values. With these parameters,
an ASD containing posaconazole and vinyl acetate yields a 32-fold
enhancement which presumably results in a reduction of NMR measurement
time by âŒ1000. This boost in signal intensity enables the full
assignment of the natural abundance pharmaceutical formulation through
multidimensional correlation experiments